The biggest revelation in teen sensation Britney Spears' feature film debut is not that the nubile pop star can actually act -- she can't -- but that, at least for a little while, the movie is better than anyone could've expected. Director Tamra Davis has smartly populated Crossroads with a natural, unforced supporting cast to help the bubbly-but-wooden Spears fight her way through Shonda Rhimes' rigidly schematic script. Once Spears' Lucy hits the road with her pals, the movie settles into a comfortably giddy, chick-flick groove: Giggly conversations about boys, sex, and weight problems are interspersed with car radio sing-alongs, and while far from deep, the talk and situations are at least buoyant and wholly believable. To this end, Davis is aided by ace cinematographer Eric Alan Edwards (Kids, My Own Private Idaho), whose handheld shots, bleached-out vistas, and bright contrasts manage to lend a verisimilitude to even the most saccharine scenes. Unfortunately, after stumbling once -- with a pointless subplot involving Lucy's bitter birth mother (Kim Cattrall) -- Crossroads takes a turn for the far, far worse when the girls reach their L.A. destination. All of the bright, poppy good will Davis worked so hard to achieve is dashed off with a series of ridiculous plot twists and revelations; the icing on the cake is an airbrushed finale that's lifted straight out of Star Search, circa 1989. Crossroads is by no means a debacle -- Spears' movie career will survive this, and more importantly, so will the careers of her talented co-stars Taryn Manning, Zoe Saldana, and Anson Mount -- but the real crime is that it stops just short of being passable entertainment.